While the federal scientists behind the study stand by their findings, some, including experts from the National Institutes of Health are raising questions about the study. They’re calling the conclusions flawed.

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The research, conducted by the U.S. National Toxicology Program, adds fuel to a long-running debate about whether cellphone radiation can cause cancer.

According to CBS News, researchers in this case tested "the health effects of radiofrequency radiation (RFR) at frequencies and modulations used in the U.S. telecommunications industry. The lab rats were exposed to cellphone-like radiation, 10 minutes on and 10 minutes off for a total of 9 hours a day, beginning in utero and continuing throughout their lives."

After reviewing the numbers, the study found a slight increase in risk; "low incidences" of two types of cancers in 2 to 3 percent of the males studied. No increase in cancer was detected in female rats.

"Overall we feel that the tumors are likely to be related to the exposures," Dr. John Bucher, associate director of the National Toxicology Program said.